There may be cases where buildings are collapsed by an earthquake, so that people left in the buildings are buried under rubble. Rescue parties remove the rubble to rescue survivors. This operation takes so much time that many people die while waiting for the rescue. It is therefore important to early find out survivors in a disaster.
A robot that moves in rubble to search for survivors with camera images, a carbon dioxide sensor, or an infrared sensor that reacts body heat has been proposed (refer to Nihon Keizai Shimbun, Jul. 14, 2002; p. 28). The robot moves into a place where a rescue party cannot enter (a narrow place, a place filled with poisonous gases, etc.) to find out survivors. The rescue party can locate the position of the robot, or the position of a survivor, by radio waves transmitted by the robot. The use of the robot allows survivors to be rescued by removing local rubble. It is also expected to use the robot for life-sustaining operation including water supply and securing space.
It takes time for the robot to find out survivors by moving in rubble. Accordingly, it is desired to find out survivors earlier in view of increasing a survival rate.